A syringe, generally, is composed of an outer tube, a gasket capable of sliding in the outer tube, and a plunger operated to move the gasket. In addition, the outer tube has a barrel part, and a reduced-diameter part (port) which is provided on a distal side (tip side) of the barrel part and is reduced in diameter relative to the barrel part. Such a syringe is so configured that the gasket is moved distally by pushing a pusher into the outer tube, whereby a liquid medicine stored in the outer tube is guided through an opening of the port to the exterior of the outer tube (refer to, for example, Patent Document 1).
The syringe described in Patent Document 1 is used, for example, as follows. With a puncture needle connected to the port, a outer tube is gripped with four fingers other than a thumb, and the thumb is put on the pusher. In this condition, the puncture needle is made to puncture a skin, and, while maintaining this state, the pusher is pushed in by the thumb to thereby administer the liquid medicine. Also, with the puncture needle connected to the port, the outer tube is pinched with a index finger and a middle finger, and the thumb is put on the pusher. In this condition, the puncture needle is made to puncture a skin, and, while maintaining this state, the pusher is pushed in by the thumb to thereby administer the liquid medicine.
According to such a using method, however, the liquid medicine cannot be administered without carrying out two steps, namely, one step of making the puncture needle to puncture a skin and maintaining this state and the other step of pushing in the pusher relative to the outer tube while maintaining the position of the outer tube relative to the skin. Besides, operating the pusher is attended by weakening of force for fixing the outer tube, whereby the puncture depth of the needle may be varied. Thus, there are problems that the conventional syringe is poor in operability and is difficult to use.
Patent Document 1: Japanese Patent Laid-open No. 2004-97640